1. Field of the Invention
This invention relates to the novel compound L-phenylalanine 1/2 sulfate and to a process for recovering L-phenylalanine (L-Phe) from a fermentation broth containing L-phenylalanine which employs crystallization of the 1/2 sulfate salt.
2. Description of the Prior Art
L-Phenylalanine has usually been recovered from L-phenylalanine-producing fermentation broths by treating the broth with an ion-exchange resin followed by repeated crystallization of the L-phenylalanine eluted from the ion-exchange resin. One of the problems of this method is the low rate at which impurities are removed in the crystallization steps. This low removal rate may be attributed to several factors including insufficient removal of mother liquor from the crystals, caused by the flake-like crystalline form of L-phenylalanine, and adsorption of colored substances and other impurities by the crystals because of strong van der Waals force between impurities and L-phenylalanine. Consequently, it is necessary to increase the number of crystallization steps. This, in turn, complicates the process of separating L-phenylalanine and lowers its yield.